The present invention relates to a system for selecting a predetermined portion of an input analog waveform and coupling only the selected portion to the output. Settings are incorporated for selecting the initiation or start point of the selected portion of the input waveform to be either on a positive or a negative slope, and an additional setting is provided for independent adjustment of the amplitude at which the selection commences. This amplitude may be either positive or negative. Similarly, settings are provided so that the selected portion of the input analog waveform may be terminated on either a positive or a negative slope, and again, independent settings determine the amplitude of the termination or end point of the selected portion of the input waveform.
The principal object of the present system is to isolate a preselected portion of an input analog waveform. Such waveform may be, but not necessarily is periodic; and it may be either coherent or non-coherent such as a pulse. The isolated portion of the analog waveform may then be subjected to further analysis or study.
The present invention has been used to study the pressure wave of the left ventricle of the heart, which wave was recorded from a standard cardiac pressure transducer.
A typical or normal left ventricle pressure wave has an origin in the range of -5 to +5mmHg and rises rapidly to 100mmHg or more. It was originally desired to isolate the wave segment between +15mmHg and +75mmHg. This information is then fed to an integrator which accumulated information for 1 minute--that is, for 60 to 80 heartbeats. From this information, and knowing the total number of heartbeats, a convenient estimation could be made and the average time required for the early phase of heart contraction. This, in turn, permitted a study to be made of the average contraction velocity under different conditions such as heart failure, drug influences, etc.